Intro to organic + Alkanes (P2+P3) Flashcards
General formula of Alkanes
CnH2n+2
General formula of Alkenes
CnH2n
2 features of a homologous series
similar chemical properties
same functional group
Define structural formula
2 molecules which have the same molecular formula but have different structural formula
Define Stereoisomerism
2 molecules which have the same structural formula but different arrangement of atoms in space
For a molecule to have E/Z isomerism it must
have a double bond which restricts rotation
each carbon in a double bond must have 2 different groups bonded.
Saturated compounds only contain…
single bonds
As chain length increases the…
boiling point increases
more electrons
stronger VDW between molecules
As the amount of branching increases the…
boiling point decreases
less surface contact
weaker VDW between molecules
Process of separating alkanes from a group of compounds
fractional distillation
Outline the essential features of fractional distillation of crude oil that enable the crude oil to be separated
all hydrocarbons have different boiling points
BP depends on the length of the Hydrocarbon
hotter at the bottom, cooler at the top
heavier hydrocarbons distilled off at bottom, lighter distilled off at the top
Why do oil companies need to crack heavy fractions
higher demand for shorter chain alkanes and alkenes
Thermal cracking produces
2 alkenes and 1 alkane
2 conditions for thermal cracking
high temp 700K - 1200K
high pressure 7000 kPa
Catalytic cracking produces
high % branched alkanes and cycloalkanes
